The present application incorporates by reference the whole of the applicants co-pending applications AU2005904181, AU 2005904196 and AU 2005904198.
As outlined in these co-pending applications, sterilization processes and apparatus that address the following criteria are highly desirable:
(a) avoid the need for vacuum
(b) avoid the need for a rinsing step
(c) avoid the need for temperatures above 60° C.
Many of the process of the prior art employ vacuum and or rinsing steps. These have the effect of increasing the complexity and cost of the apparatus required, and can lengthen the time of the disinfection or sterilization process considerably (meaning more downtime for expensive medical instruments). The use of high temperatures can also increase the complexity and cost of sterilization instruments, but more importantly, it can damage many materials.
It is desired to provide disinfecting methods and apparatus that meet these criteria, while achieving the highest possible efficacy in pathogen destruction, especially when treating occluded, mated and lumen surfaces.
It is desirable that the disinfecting methods use hydrogen peroxide. Hydrogen peroxide at low concentrations is safe to transport, sell and handle and is extremely well known, with little or no regulatory barriers to its use. However, there are problems with those methods which require high concentration hydrogen peroxide as a starting material. For example, commercial vapour and plasma processes use as a starting material corrosive and irritating 60% peroxide solutions which requiring special packaging and handling precautions.
When hydrogen peroxide is used in the form of small droplets (sprayed, ultrasonically nebulized, etc), the particles have a tendency to deposit as droplets on surfaces and the residual layer of peroxide is a potential problem. Medical instruments, food packaging and other disinfected items need to be stored dry to avoid re-contamination. Importantly, surgical instruments must not contain residual peroxide at levels higher than 1 microgram/sq·cm.
However, eliminating residual peroxide is very difficult. It requires either washing which introduces the associated problems previously discussed in our copending applications in connection with liquid systems, prolonged periods of high temperature drying (which completely negate any advantages arising from fast kill times and low process temperature) or requires use of catalase or other chemical means to decompose peroxide (which still requires drying and which creates a series of problems with the residual chemicals left on instruments) or the use of vacuum. Accordingly, it is desirable to provide a system that uses the minimum possible amount of peroxide to achieve a desired effect.
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.